The project's aim is to document and interpret the trend toward increasing 24-hour activity in cities. Three aspects receive attention: 1) An activities time-census: A survey listing and classifying types of activity going on around the clock. 2) Cycles of human problems: Classification and analysis of the timing of human problems throughout the 24-hour period. The data will be assessed for cyclic features, phase relationships, and possible utility in an indicator of psychosocial needs of city dwellers. 3) System evolution and functioning: Analysis of data on urban activity around the clock in order to: (a) interpret the 'frontier' aspects of expansion into the night. (b) identify phase relationships among functions and behavior; (c) anticipate future urban settings that may grow out of the present circumstances.